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Title: Enhanced thermal conductance of polymer composites through embedding aligned carbon nanofibers

Abstract

The focus of this work is to find a more efficient method of enhancing the thermal conductance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 μm and a higher thermal conductance between 25–40 μm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers

Authors:
 [1];  [2];  [1]
  1. Utah State Univ., Logan, UT (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1346645
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
AIMS Materials Science (Online)
Additional Journal Information:
Journal Name: AIMS Materials Science (Online); Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2372-0484
Publisher:
AIMS Press
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Thermal interface material; Thermal conductance; Composite; Carbon nanofiber; Polymer

Citation Formats

Nicholas, Roberts, Hensley, Dale K., and Wood, David. Enhanced thermal conductance of polymer composites through embedding aligned carbon nanofibers. United States: N. p., 2016. Web. doi:10.3934/matersci.2016.3.851.
Nicholas, Roberts, Hensley, Dale K., & Wood, David. Enhanced thermal conductance of polymer composites through embedding aligned carbon nanofibers. United States. doi:10.3934/matersci.2016.3.851.
Nicholas, Roberts, Hensley, Dale K., and Wood, David. 2016. "Enhanced thermal conductance of polymer composites through embedding aligned carbon nanofibers". United States. doi:10.3934/matersci.2016.3.851. https://www.osti.gov/servlets/purl/1346645.
@article{osti_1346645,
title = {Enhanced thermal conductance of polymer composites through embedding aligned carbon nanofibers},
author = {Nicholas, Roberts and Hensley, Dale K. and Wood, David},
abstractNote = {The focus of this work is to find a more efficient method of enhancing the thermal conductance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 μm and a higher thermal conductance between 25–40 μm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers},
doi = {10.3934/matersci.2016.3.851},
journal = {AIMS Materials Science (Online)},
number = 3,
volume = 3,
place = {United States},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
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  • Vertically aligned carbon nanofibers (VACNFs) have been grown using a low-pressure, plasma-enhanced, chemical vapor deposition process. The nanofibers are grown from a nickel catalyst that can be patterned to form arrays of individual, isolated VACNFs. The fibers are grown at pressures below 100 mTorr, using an inductively coupled plasma source with a radio-frequency bias on the sample substrate to allow for independent control of the ion energies. Plasma conditions are related to growth results by comparing optical emission from the plasma to the physical structure of the nanofibers. We find that the ratio of etching species in the plasma tomore » depositing species is critical to the final shape of the carbon structures that are formed.« less
  • Highlights: {yields} The CNFs improve the infiltration rate and thermal properties of carbon/carbon composites. {yields} The densification rate increases with the CNF content increasing at the beginning of infiltration. {yields} The values of the thermal conductivity of the composite obtain their maximum values at 5 wt.%. -- Abstract: Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated using the electrified preform heating chemical vapor infiltration method (ECVI) under atmospheric pressure. Initial thermal gradients were determined. Resistivity and density evolutions with infiltration time have been recorded. Scanning electronmore » microscopy, polarized light micrograph and X-ray diffraction technique were used to analyze the experiment results. The results showed that the infiltration rate increased with the rising of CNF content, and after 120 h of infiltration, the density was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 wt.% to 20 wt.%. CNF-reinforced C/C composites have enhanced thermal conductivity, the values at 5 wt.% were increased by nearly 5.5-24.1% in the X-Y direction and 153.8-251.3% in the Z direction compared to those with no CNFs. When the additive content was increased to 20 wt.%, due to the holes and cavities in the CNF web and between carbon cloth and matrix, the thermal conductivities in the X-Y and Z directions decreased from their maximum values at 5 wt.%.« less
  • This paper investigates the thermal contact conductance across carbon fiber/epoxy resin composites under vacuum conditions at discrete contact pressures. Samples with unidirectional, continuous fibers oriented at 0 and 90 degrees to the contact interface are analyzed in 0/0 and 90/90 test configurations. Experimental results are compared with analytical data obtained using theory developed for homogeneous, isotropic, metallic contacts. As with earlier experiments in air, variations in the experimental data show the importance of material anisotropy and heterogeneity in governing thermal contact conductance between composites. While metallic theory can incorporate the anisotropic influence of fiber orientation, it fails to account formore » the distinct contributions of both fiber and matrix to the composite contact problem. 21 refs.« less
  • Multiwalled-carbon nanotubes (MWCNTs) are grown on top of vertically aligned carbon nanofibers (VACNFs) via microwave plasma-enhanced chemical vapor deposition (MPECVD). The VACNFs are first grown in a direct-current plasma-enhanced chemical vapor deposition reactor using nickel catalyst. A layer of carbon-silicon materials is then deposited on the VACNFs and the nickel catalyst particle is broken down into smaller nanoparticles during an intermediate reactive-ion-plasma deposition step. These nickel nanoparticles nucleate and grow MWCNTs in the following MPECVD process. Movable-probe measurements show that the MWCNTs have greatly improved field-emission properties relative to the VACNFs